This 4-year, randomized, controlled clinical trial will investigate the impact of stop-smoking treatment on drug/alcohol abuse inpatients. Stop-smoking treatment will be offered to cigarette smoking, drug/alcohol abuse inpatients of a residential treatment program for homeless veterans. Volunteers (N - 150) will be randomly assigned to one of three stop-smoking treatment conditions: (1) a multicomponent stop-smoking treatment consisting of standard smoking cessation strategies; (2) the same multicomponent treatment with a specialized component that uses the smoking cessation experience as an opportunity for in vivo practice and generalization training of relapse prevention skills; or (3) an attention-control treatment consisting of stop-smoking bibliotherapy and nondirective counseling. Inpatients who do not volunteer for stop-smoking treatment, but who agree to participate in the study assessment procedures (N - 50) also will be studied to determine if volunteers for stop-smoking treatment differ from nonvolunteers on pretreatment measures, inpatient treatment course, or posttreatment drug/alcohol abuse. Treatment outcome will be assessed for both cigarette smoking and drug/alcohol use. Objective biochemical and self-report assessments will be conducted throughout the inpatient program, and at paid follow-ups 3, 6, 9, and 12 months after discharge from the residential treatment program. Data from the proposed study will provide critical information about the feasibility and treatment efficacy of stop-smoking treatment for inpatient drug/alcohol abusers, the impact of the stop-smoking program on the course of inpatient treatment and postdischarge drug/alcohol use, and the incremental impact of special therapeutic techniques designed to enhance generalization of positive treatment effects from smoking to drug/alcohol use. In addition, this study will provide important information about the commonalities between nicotine and other dependence-producing drugs. Such information may ultimately contribute to a unified theory of substance abuse, improved treatment outcome and reduced health risks among drug/alcohol abusers who smoke.